You can enter the Recovery mode by pressing Home, Volume and Power buttons in different combinations for different smartphones.
But you can also reboot to Recovery Mode without pressing the combination of buttons on CyanogenMod. It can be quite useful, for instance, if you have a button broken or you don’t know the combination for your particular model or if it is simply unhandy to press those three buttons simultaneously. Here is how to reboot into Recovery in CM12 / CM13. This method can also work for some versions of stock Android 5 and 6.